The present invention relates to a disk for use in a turbine engine component having a plurality of locking slots in a bearing surface and a system and method for assembling the turbine engine component.
Gas turbine engine have a plurality of compressors arranged in flow series, a plurality of combustion chambers, and a plurality of turbines arranged in flow series. The compressors typically include at least a high pressure compressor and a lower pressure compressor which are respectively driven by a high pressure turbine and a low pressure turbine. The compressors compress the air which has been drawn into the engine and provide the compressed air to the combustion chambers. Exhaust gases from the combustion chambers are received by the turbines which provide useful output power. Each compressor typically has a plurality of stages.
The main components of a typical tangential stage in a high pressure compressor are the disk, the blades, the ladder seals and the locks. The assembly sequence for a typical tangential stage is as follows. First, a ladder seal is assembled to the inner rail of the disk with a first slot of the ladder seal positioned directly over the loading slot in the disk. Second, a first blade is assembled through the ladder seal and through the loading slot in the disk. Then the blade and ladder seal are rotated around the circumference of the disk until the next slot of the ladder seal is positioned directly over the loading slot. In a similar fashion, the next blade is loaded and rotated. Once the blades have been completely loaded and rotated in the ladder seal segment, the lock is assembled through the load slot and rotated to the lock slot position and tightened. The lock prevents the circumferential motion of the blades, which insures that work will be done on the air and that the blades will not come back out through the load slot.
Since locking and loading slots form discontinuities in tangential rotor disks, they have been known to initiate thermal mechanical fatigue (TMF) cracking. The root cause of any TMF cracking is the thermal gradients that exist at certain flight points. One flight point may produce a cold bore and a hot rim, which would put the rim into compression. Another flight point may produce a hot bore and a cold rim which would put the rim into tension. This cyclic loading fatigues the disk. The locking and loading slots may make this condition worse by introducing stress concentrations due to the discontinuities.